<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户搜索</title>
    <style type="text/css">
        .content {
            width: 643px;
            margin: 100px auto;
            text-align: center;
        }

        input[type='text'] {
            width: 530px;
            height: 40px;
            font-size: 14px;
        }

        input[type='button'] {
            width: 100px;
            height: 46px;
            background: #38f;
            border: 0;
            color: #fff;
            font-size: 15px
        }

        .show {
            position: absolute;
            width: 535px;
            height: 100px;
            border: 1px solid #999;
            border-top: 0;
            display: none;
        }
    </style>
</head>
<body>
<form autocomplete="off">
    <div class="content">
        <img src="img/logo.jpg">
        <br/><br/>
        <input type="text" id="username">
        <input type="button" value="搜索一下">
        <div id="show" class="show"></div>
    </div>
</form>
</body>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
    $("#username").mousedown(function(){
        let username = $("#username").val();
        if(username==null || username==""){
            return
        }
        $.ajax({
            url:"userServlet",
            data:{"username":username},
            type:"post",
            dataType:"json",
            success:function(data){
               let names = "";
               for(let i=0; i<data.length;i++){
                   names +="<div>"+data[i].name+"</div>";
               }
               $("#show").html(names);
               $("#show").show();
            }
        })
    })
</script>
</html>